Low Temperature Co-fired Ceramic (LTCC) technology is an electronic packaging platform especially suitable for high frequency system level packaging applications. A typical LTCC circuit substrate is formed by laminating multiple layers of ceramic tape under pressure and then fired at high temperatures in the range of 800 to 900 degrees C. On firing, LTCC forms a monolithic circuit containing electrical interconnections and provides for a highly reliable integrated circuit chip carrier platform. Electrical interconnections on LTCC substrates are generally formed by using thick film metallizations of gold, silver, or copper metals. Being a ceramic material, LTCC is a high reliability system and also has very good thermal properties in addition to extremely low dielectric loss for electrical signals. LTCC has a coefficient of thermal expansion (CTE) relatively close to that of semiconductor materials used for fabricating chips thereby making high reliability flip chip attachment possible.
A transceiver is a system that combines the functions of a transmitter and receiver in the same circuit. A practical transceiver circuit is realized with a set of Millimeter Wave Integrated Circuit (MMIC) chips, interconnect metallizations patterned according to strict geometric requirements, passive components such as resistors, capacitors, and inductors, metal patterns forming antenna elements and arrays, and antenna networks. Each of these sub systems and components impose somewhat conflicting performance requirements on package configurations.
State of the art transceiver packaging solutions use different materials within the same package due to differing requirements imposed by various subsystems. For example, reliable flip chip attachment require a ceramic substrate while good antenna performance required a low dielectric constant and hence the use of organic laminates. The multi-material packaging approaches result in complex package configurations resulting in performance impairments and expensive solutions. Both higher performance and lower cost can be realized if a single substrate packaging solution can be provided. The concepts described here offer such high performance and lower cost package approaches.